Detection of Nutritionally Driven Live Weight Changes in Dairy Ewes Using a Walk-over-Weighing System

Seasonal variability in feed availability in Mediterranean dairy sheep systems can compromise animal performance and welfare, highlighting the need for reliable, high-frequency monitoring tools. Live weight (LW) is a key indicator of nutritional status, but conventional measurements are labour-intensive and poorly suited to dynamic conditions. Walk-over-weighing (WoW) systems integrated with electronic identification (EID) enable automated, continuous, individual-level LW monitoring. This study assessed the sensitivity of a WoW system to detect nutritionally driven LW changes in Sarda dairy ewes under indoor and grazing conditions. Two experiments were conducted: an indoor short-term nutritional challenge involving 24 non-lactating ewes and a grazing trial with contrasting pasture access times involving 48 lactating ewes. In both experiments, the WoW system detected consistent LW differences between nutritional treatments (p < 0.001), capturing both short-term responses and sustained LW dynamics. Differences were approximately 5%, indicating that the WoW system was sensitive to nutritionally induced LW variation under the experimental conditions of the present study, before marked changes in body condition score (BCS) became detectable. These results demonstrate that WoW systems can reliably capture LW trajectories in response to nutritional variation. However, LW responses should be interpreted cautiously, as short-term variation may also reflect gut fill and hydration dynamics, and intake information was not fully available at the individual level because some feed intake components were measured at the group level or estimated indirectly. Integrating automated LW data with production and management information may support group-level nutritional decisions and early detection of animals deviating from expected LW trajectories in precision dairy sheep systems.